1. Field of the Invention
The present invention relates to improvements in tamper-evidencing closures including tamper-evidencing bands such as those commonly used as bottle caps.
2. Description of Related Art
U.S. Pat. No. 4,801,031 to Barriac discloses a tamper-indicating closure that includes an inwardly folded tamper-indicating band with intermittent pleats, around the inwardly folded portion of the band. The pleats are inwardly directed and spaced around the circumference of the band. U.S. Pat. No. 5,400,913 to Kelly discloses a similar tamper-indicating closure that also has an inwardly folded tamper-indicating band with continuous pleats around the inwardly folded portion of the band.
As discussed in the Kelly '913 patent, the tamper-indicating band should slip over the locking bead or rim of the container neck without damaging the frangible connection between the band and the skirt of the closure. The tamper-indicating band must be sufficiently elastic in order to avoid too great a resistance when closing the bottle, which could damage the frangible connection. However, the tamper-indicating band should be sufficiently stiff in order to reliably engage the locking bead of the container neck and thereby hold the band beneath the locking bead when opening the closure, so that the tamper-indicating band will sever the frangible connection.
The Kelly '913 patent improves the flexibility of the inwardly folded pleated portion of the band in two ways. One, a frangible connection is provided between each pleat. The frangible connections between the pleats ensure high elasticity of the tamper-indicating band during closure. Alternatively, individual bridges, instead of a frangible connection, are provided between the pleats. The bridges are relatively easily damaged during opening of the closure, thus improving the tamper-indicating nature of the closure.
It has been determined by the applicant herein that the inwardly-turned pleated designs of both the Barriac '031 patent and the Kelly '913 patent have a tendency to improperly grip the locking bead of the container neck and, thereby allow the tamper-indicating band to slip back upwardly over the locking bead upon opening of the closure, which defeats the tamper-indicating aspect of the designs. The present invention improves upon this aspect of prior art pleated tamper-indicating bands.
It is also known for the internal thread pattern of a bottle cap to include spaced gaps around the spiral thread bead for the purpose of reducing weight of the bottle cap as well as to simplify tooling production required to manufacture the bottle caps. The present invention also provides an improved spiral thread pattern and design.
A further problem encountered with tamper-evidence closures is that the tamper-indicating band and inwardly turned retaining rim can trap liquid in the closure. Thus, product used to fill the container can spill on the container neck and when the container is closed by the closure or cap, the liquid product trapped by the inwardly turned retaining rim. Similarly, in many instances the container will be washed after capping, and the wash water can become trapped in the cap. In either case, and particularly for products which contain sugar, the trapped liquid can act as a habitat for the growth of bacteria, mold and the like.
A further problem encountered with tamper-evidence closures is that the plug of the tamper-indicating closure may not sufficiently seal against the closure in the event that the closure is applied such that it is cross-threaded with respect to the container. Additionally, the application forces necessary to apply prior closures often is not constant and may fluctuate increasing the likelihood that the closure will cross-thread as it is applied to the container. Additionally, upwardly and inwardly turned retaining rims of prior tamper-evidencing bands often remain on the container neck as the closure is removed from the container thus requiring the removal of the band prior to washing the container for recycling purposes. Furthermore, prior methods of forming tamper-evidencing closures having an inwardly and upwardly directed retaining rims were subject to the possibility of the molded closure from failing to demold entirely from prior molding apparatus thus requiring additional steps to remove the closure from the molding apparatus.